打开 jdialog 后更新 jlabel 文本

Question

我必须查询数据库以获取数据写入 JLabel 并加速打开对话框

我创建了没有文本的 JLabel，并在完成 SwingWorker 过程后设置了文本

但 JLabel 文本未更新

有什么办法可以做到这一点

这是我对话框的源代码：

package com.caisse.caisseFrame.dialogs;

import java.awt.Dimension;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Image;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.IOException;

import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JLabel;
import javax.swing.SwingWorker;

import com.caisse.ConnectDB;
import com.caisse.CustomComponent.JButtonCustom;
import com.caisse.CustomComponent.JPanelCustom;
import com.caisse.caisseFrame.CaisseFrame;
import com.soqop.caisse.dao.TicketDAO;

public class LectureXDialog extends JDialog {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    JButton ok_btn;
    TicketDAO ticketDAO;

    public LectureXDialog(final CaisseFrame parent) {
        setAlwaysOnTop(true);
        setSize(new Dimension(300, 280));
        setLocationRelativeTo(parent);
        setTitle("Lecture X");
        setVisible(true);
        setModalityType(ModalityType.DOCUMENT_MODAL);
        parent.setEnabled(false);

        ticketDAO = new TicketDAO(ConnectDB.getInstance());

        final JPanelCustom componentsPanel = new JPanelCustom();
        GridBagLayout componentsPanelLayout = new GridBagLayout();
        componentsPanel.setLayout(componentsPanelLayout);

        final JLabel lectureXlabel = new JLabel();
        lectureXlabel.setFont(new Font("Cambria", Font.BOLD, 24));
        lectureXlabel.setPreferredSize(new Dimension(250, 55));
        lectureXlabel.setMinimumSize(new Dimension(250, 55));
        GridBagConstraints gbc_lectureXlabel = new GridBagConstraints();
        gbc_lectureXlabel.insets = new Insets(2, 2, 2, 2);
        gbc_lectureXlabel.gridx = 0;
        gbc_lectureXlabel.gridy = 0;
        gbc_lectureXlabel.anchor = GridBagConstraints.CENTER;
        componentsPanel.add(lectureXlabel, gbc_lectureXlabel);

        ok_btn = new JButtonCustom("ok");
        ok_btn.setFont(new Font("Cambria", Font.BOLD, 24));
        try {
            Image img = ImageIO.read(getClass().getResource("/resources/ok.png"));
            ok_btn.setIcon(new ImageIcon(img));
        } catch (IOException e1) {
            e1.printStackTrace();
        }
        ok_btn.setPreferredSize(new Dimension(150, 55));
        ok_btn.setMinimumSize(new Dimension(150, 55));
        ok_btn.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                parent.setEnabled(true);
                parent.setFocus();
                LectureXDialog.this.dispose();
            }
        });
        GridBagConstraints gbc_ok_btn = new GridBagConstraints();
        gbc_ok_btn.insets = new Insets(2, 2, 2, 2);
        gbc_ok_btn.gridx = 0;
        gbc_ok_btn.gridy = 1;
        componentsPanel.add(ok_btn, gbc_ok_btn);

        add(componentsPanel);

        addWindowListener(new java.awt.event.WindowAdapter() {
            @Override
            public void windowClosing(java.awt.event.WindowEvent windowEvent) {
                parent.setEnabled(true);
                parent.setFocus();
                LectureXDialog.this.dispose();
            }
        });


        SwingWorker worker = new SwingWorker<Boolean, Void>() {
            String text = "";
            @Override
            public Boolean doInBackground() {
                    text = "<html><center>Lecture X : " + ticketDAO.getLectureX() + "</center></html>";
                return true;
            }

            @Override
            public void done() {
                lectureXlabel.setText(text);
                lectureXlabel.revalidate();
                lectureXlabel.repaint();
                componentsPanel.revalidate();
                componentsPanel.repaint();
                getContentPane().revalidate();
                getContentPane().repaint();
            }
        };

    }

}

Answer 1

要让您的 Swing Worker 执行后台工作，您需要调用 SwingWorker#execute() 方法。如果你不添加它，那么……它就不知道什么时候开始工作了。它就像任何其他变量一样：

JLabel label = new JLabel("Hello world");

但是如果你从来没有将 label 添加到任何东西（或者像 ActionListener 没有添加到 JButton）它永远不会被添加/执行。

worker.execute();

在你的构造函数中或任何你希望它开始工作的地方。

根据@MadProgrammer 的评论：

Remember, SwingWorker can return data, so instead of returning Boolean, you could return String and use get in the done method to get the returns of the worker, somewhat safer and more usable then using an instance field

他指的是像这样更改您的工人代码：

SwingWorker worker = new SwingWorker<Boolean, Void>() {
    @Override
    public String doInBackground() {
        return "<html><center>Lecture X : " + ticketDAO.getLectureX() + "</center></html>";
    }

    @Override
    public void done() {
        lectureXlabel.setText(get());
        lectureXlabel.revalidate();
        lectureXlabel.repaint();
        componentsPanel.revalidate();
        componentsPanel.repaint();
        getContentPane().revalidate();
        getContentPane().repaint();
    }
};

打开 jdialog 后更新 jlabel 文本

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